This is a Universal App which will run on the iPhone, iPod Touch, and iPad.

* Featured by Apple in ‘What’s Hot’ in 76 countries(1)

* Now displays automatic weather calculation based on iPhone/iPad localization features with available internet access. Just press the Fetch button.

The Heat Index and Relative Humidity Calculator is a tool for measuring the perceived temperature and relative humidity. Because the body normally cools itself by perspiration, when relative humidity is high, the evaporation rate is reduced, and heat is removed from the body at a lower rate causing it to retain more heat than it would in dry air.

Relative humidity may be defined as the ratio of the water vapor density (mass per unit volume) to the saturation water vapor density, and in the case of this iPhone App it is expressed as a percentage. The air temperature and dew point can be entered as Fahrenheit or Celsius.

The calculator will compute both the relative humidity and the heat indexThe calculator will compute both the relative humidity and the heat index when the values for the air temperature and dew point are entered.

The results can also be emailed through the iphone’s email application. The application is completely compatible with the iPhone OS 3 and later, as well as the iPod Touch.

The heat category is a measurement taken from NOAA’s National Weather Service Heat Index Chart and is used to assist in determining how much caution should be exercised when outdoors for any period of time.

The calculator is the most effective when the temperature is at least 80 °F / 26 °C and the relative humidity is at least 40%.